Though often flat, Jersey Boys does pick up during the musical numbers, where the pitch-perfect clone ensemble strut their stuff. (Keith Bernstein/Warner Bros. Entertainment Inc. and RatPac Entertainment)

Though often flat, Jersey Boys does pick up during the musical numbers, where the pitch-perfect clone ensemble strut their stuff.(Keith Bernstein/Warner Bros. Entertainment Inc. and RatPac Entertainment)

Of all the obstacles and indignities overcome by the doo-wop-dipped New Jersey quartet the Four Seasons on their way to pop-nostalgic musical immortality, Clint Eastwood’s flat-as-a-platter adaptation of Marshall Brickman and Rick Elice’s Broadway jukebox musical-bio must now be counted as another. However, if Frankie Valli’s heavenly falsetto can rise above even this sticky cinematic treatment, it truly is an instrument of divine power.

Most conspicuous of Eastwood’s hurdles laid before the band, the play and his audience is the movie’s resolute refusal to do anything than the bare minimum of what’s required, which is to put his cast – comprised largely of relatively unknown veterans of the nine-year-old Broadway blockbuster’s touring productions – in front of a camera and shoot. Much as one might wait and hope for a visual correlative of the Four Seasons’ gravity-defying musical sweetness to emerge, Eastwood keeps almost the entire movie – 2 1/4 hours or so worth – grounded in an aesthetic that recalls American network TV circa 1972. Even when confronted with the play’s most playful departures from bread-and-butter dramatic exposition – as when the various members turn to the camera to narrate their allotted portion of the band’s four historical “seasons” – Eastwood opts for the most pedestrian strategy possible: The guys simply turn to the camera and, well, narrate. Trust me, you’ve watched condominium lobby channels that are more exciting than this.

While the movie perks up somewhat during the musical numbers, and the pitch-perfect clone ensemble (John Lloyd Young as Frankie Valli, Vincent Piazza as Tommy DeVito, Michael Lomenda as Nick Massi and Erich Bergen as Bob Gaudio – are permitted to strut the stuff they were presumably cast for, Jersey Boys is otherwise an almost perversely inert movie experience, from the sets that feel like a backlot bus tour, hairpieces that practically smell of cosmetic glue, and a riot of final-act, old-age makeup that recalls an especially devoted gathering at a Tim Conway fan convention. To take an especially vexing case in point, Eastwood’s sole gesture toward star casting is the appearance of the transcendentally eccentric Christopher Walken as the more-than-shady band mentor, mob go-between and father figure Gyp DeCarlo. Surely, one says to oneself when this pale-eyed spectral oddball walks so welcomely on screen, now the movie must take flight, only to slump back in one’s seat as Walken just keeps on walkin’ – in one door in most scenes, and then straight out another.

The real mystery of all this is the constant and all-too-easy imagining of the infinitely better movie Jersey Boys might have been, particularly considering the play’s built-in supply of mob intrigue, plate-smashing, kitchen-sink domestic squabbles, up-from-the-street showbiz clichés, and enough ripe urban Jersey Italianese to give The Sopranos a run for its laundered money. Originally slated to be directed by Jon (Iron Man I and 2) Favreau, who might at least have taken greater care to ensure those hairpieces didn’t look like freshly fallen squirrel pelts, Jersey Boys would have made a tantalizing project for somebody like Scorsese, Baz Luhrmann, P.T. Anderson, or anybody capable of taking the play and cranking its hoarier showbiz conventions into the same state of giddy bubblegum delirium the music itself attains. And that, more than anything else, is the movie’s most imponderable and frustrating liability: It never reaches the soaring, cloud-busting heights of Frankie Valli’s otherworldly falsetto, and it doesn’t even try.